Using ranging over c-v2x to supplement and enhance gps performance

ABSTRACT

On-board equipment in a motor vehicle includes a C-V2X communication device receiving a first signal from road side equipment having a known position. The C-V2X communication device transmits a second signal having content that is dependent upon a length of time in which the first signal traveled from the road side equipment to the C-V2X communication device. A GPS device is communicatively coupled to the C-V2X communication device and receives the second signal from the C-V2X communication device. The GPS device estimates a position of the vehicle. The estimating is dependent upon the second signal from the C-V2X communication device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/597,497, filed on Dec. 12, 2017, which the disclosure of which ishereby incorporated by reference in its entirety for all purposes.

FIELD OF THE INVENTION

The disclosure relates to determining the global position coordinates ofa motor vehicle.

BACKGROUND OF THE INVENTION

An on-board unit (OBU) is the part of a Cellular-Vehicle-To-All (C-V2X)system that is installed in a moving vehicle. On-board equipment (OBE)contains other equipment in addition to the OBU, such as a human machineinterface unit and other communication equipment for the vehicle. A roadside unit (RSU) is the part of the C-V2X system that is installed on theside of the road. Road side equipment (RSE) contains the RSU in additionto other equipment to link the RSU to the backend network that may behosted in the cloud.

Position accuracy is a vital parameter in the implementation and successof C-V2X technology. However, position accuracy may be reduced if theGPS receiver cannot accurately determine its location due to a weaksignal or travelling in a tunnel.

SUMMARY

The present invention may implement ranging over the C-V2X communicationchannel to enhance GPS performance in a motor vehicle. The C-V2X devicein the vehicle may communicate with a C-V2X base station or with RSU.Both the RSU and the base station have a known location. The C-V2Xdevice in the vehicle can accurately calculate its proximity or locationfrom the RSU or from the base station each time the C-V2X devicereceives a signal. Also, by knowing the exact frequency used in thechannel, and knowing the time of arrival of the signal, one cancalculate the displacement offset from the last reference point whenthis calculation was last performed. This displacement offsetinformation can supplement GPS location if the GPS receiver cannotaccurately determine its location due to a weak signal as in the case oftravelling in a tunnel. Further, the displacement offset information canbe used to improve the GPS location fix accuracy even if the GPSreceiver is able to calculate a fix. More location information can alsobe obtained using ranging information like vehicle speed. This locationinformation combined with information from other sensors in the car maybe very useful to a dead reckoning algorithm to ultimately achievelocation accuracy on the order of centimeters, which may be needed forthe C-V2X system to achieve its safety targets. Another way to measurethe distance displacement is to measure the time difference between tworound trips of a signal in a special mode of transmission.

In one embodiment, the invention comprises on-board equipment in a motorvehicle. The on-board equipment includes a C-V2X communication devicereceiving a first signal from road side equipment having a knownposition. The C-V2X communication device transmits a second signalhaving content that is dependent upon a length of time in which thefirst signal traveled from the road side equipment to the C-V2Xcommunication device. A GPS device is communicatively coupled to theC-V2X communication device and receives the second signal from the C-V2Xcommunication device. The GPS device estimates a position of thevehicle. The estimating is dependent upon the second signal from theC-V2X communication device.

In another embodiment, the invention comprises a global positioningmethod for a motor vehicle, including the following steps performedwithin the motor vehicle. A C-V2X signal is received from road sideequipment having a known position. A distance signal is transmittedhaving content that is dependent upon a length of time in which theC-V2X signal traveled from the road side equipment to the motor vehicle.The distance signal is received. A position of the vehicle is estimated.The estimating is dependent upon the distance signal.

In yet another embodiment, the invention comprises on-board equipment ina motor vehicle. The on-board equipment includes a C-V2X communicationdevice receiving a first signal from road side equipment having a knownposition. The C-V2X communication device transmits a second signalindicative of a length of time it took for the first signal to travelfrom the road side equipment to the C-V2X communication device. A GPSdevice is communicatively coupled to the C-V2X communication device andreceives the second signal from the C-V2X communication device. The GPSdevice estimates a position of the vehicle. The estimating is dependentupon the second signal from the C-V2X communication device.

An advantage of the present invention is that it may, in OBE, reduce GPSposition error from meters to a lane-accurate level (e.g., centimeters).This is very important for robust implementation of many safety apps inthe connected industry.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention will be had uponreference to the following description in conjunction with theaccompanying drawings.

FIG. 1 is a block diagram of one example embodiment of a globalpositioning arrangement of the present invention for a motor vehicle.

FIG. 2 is a flow chart of one embodiment of a global positioning methodof the present invention for a motor vehicle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates one example embodiment of a global positioningarrangement 10 of the present invention for a motor vehicle. Arrangement10 includes a C-V2X base station/RSU 12 having a known location, and amotor vehicle 14 having a C-V2X communication device 16 and a GPS deadreckoning engine 18. Motor vehicle 14 is shown at a first position,“position 1”, at the bottom of FIG. 1, and at a second position,“position 2”, in the middle of FIG. 1. C-V2X base station/RSU 12 andmotor vehicle 14 each include a respective C-V2X antenna 20, 22. To beclear, motor vehicle 14 may be at positions 1 and 2 at different times,but cannot be at both positions 1 and 2 at the same time.

During use, C-V2X base station/RSU 12 has a pre-known position which wasdetermined when C-V2X base station/RSU 12 was permanently and fixedlyinstalled. This pre-known position may be communicated to motor vehicle14. A signal transmitted by antenna 20 may arrive at position 1, asindicated at 24; and a signal transmitted by antenna 20 may arrive atposition 2, as indicated at 26. Because position 2 is closer to antenna20 than is position 1, the signal arrives at position 2 faster than itarrives at position 1. Capturing this time delta can be translated to aposition delta based on the known speed of the signal. The calculatedposition delta or distance delta may be transmitted from C-V2Xcommunication device 16 to GPS dead reckoning engine 18, as indicated at28, and may be used by GPS dead reckoning engine 18 to improve theaccuracy of its location calculation.

The time it takes for the signal to travel from antenna 20 to antenna 22may be determined by any of a number of possible methods. For example,the signal may include the time at which the signal is transmitted fromantenna 20, and C-V2X communication device 16 may calculate thedifference between this time of transmission and the time at whichantenna 22 receives the signal.

In another embodiment, C-V2X communication device 16 may transmit aresponse signal to C-V2X base station/RSU 12 in response to receivingthe signal from C-V2X base station/RSU 12. C-V2X base station/RSU 12 maythen calculate the time difference between the time at which C-V2X basestation/RSU 12 transmitted the first signal and the time at which C-V2Xbase station/RSU 12 received the second signal. This total roundtriptime may then be transmitted to C-V2X communication device 16 for use byGPS dead reckoning engine 18 in calculating its location.

FIG. 2 illustrates one embodiment of a global positioning method 200 ofthe present invention for a motor vehicle. In a first step 202, a C-V2Xsignal is received from road side equipment having a known position. Forexample, C-V2X base station/RSU 12 has a pre-known position which wasdetermined when C-V2X base station/RSU 12 was permanently and fixedlyinstalled. This pre-known position may be communicated to motor vehicle14.

In a next step 204, a distance signal is transmitted having content thatis dependent upon a length of time in which the C-V2X signal traveledfrom the road side equipment to the motor vehicle. For example, a signaltransmitted by antenna 20 may arrive at position 1, as indicated at 24;and a signal transmitted by antenna 20 may arrive at position 2, asindicated at 26. Because position 2 is closer to antenna 20 than isposition 1, the signal arrives at position 2 faster than it arrives atposition 1. Capturing this time delta can be translated to a positiondelta based on the known speed of the signal. The calculated positiondelta or distance delta may be transmitted as a distance signal fromC-V2X communication device 16.

Next, in step 206, the distance signal is received. For example, GPSdead reckoning engine 18 may receive the distance signal, as indicatedat 28.

In a final step 208, a position of the vehicle is estimated. Theestimating is dependent upon the distance signal. For example, thedistance signal may be used by GPS dead reckoning engine 18 to improvethe accuracy of its location calculation.

The foregoing description may refer to “motor vehicle”, “automobile”,“automotive”, or similar expressions. It is to be understood that theseterms are not intended to limit the invention to any particular type oftransportation vehicle. Rather, the invention may be applied to any typeof transportation vehicle whether traveling by air, water, or ground,such as airplanes, boats, etc.

The foregoing detailed description is given primarily for clearness ofunderstanding and no unnecessary limitations are to be understoodtherefrom for modifications can be made by those skilled in the art uponreading this disclosure and may be made without departing from thespirit of the invention.

What is claimed is:
 1. On-board equipment in a motor vehicle, theon-board equipment comprising: a C-V2X communication device configuredto receive a first signal from road side equipment having a knownposition, the C-V2X communication device being configured to transmit asecond signal having content that is dependent upon a length of time inwhich the first signal traveled from the road side equipment to theC-V2X communication device; and a GPS device communicatively coupled tothe C-V2X communication device and configured to: receive the secondsignal from the C-V2X communication device; and estimate a position ofthe vehicle, the estimating being dependent upon the second signal fromthe C-V2X communication device.
 2. The on-board equipment of claim 1wherein the second signal indicates a distance dependent upon the lengthof time in which the first signal traveled from the road side equipmentto the C-V2X communication device.
 3. The on-board equipment of claim 1wherein the estimating is dependent upon an immediately previouslyestimated position of the vehicle.
 4. The on-board equipment of claim 1wherein the C-V2X communication device is configured to receive thefirst signal from a C-V2X base station.
 5. The on-board equipment ofclaim 1 wherein the GPS device is configured to provide the estimatedposition of the vehicle to another application within the motor vehicle.6. The on-board equipment of claim 1 further comprising an electronicprocessor communicatively coupled to the GPS device and configured todetermine, based upon the estimated position of the vehicle, a trafficlane in which the motor vehicle is traveling.
 7. The on-board equipmentof claim 1 wherein the estimated position of the vehicle is accurate towithin less than one meter.
 8. A global positioning method for a motorvehicle, the method comprising the following steps performed within themotor vehicle: receiving a C-V2X signal from road side equipment havinga known position; transmitting a distance signal having content that isdependent upon a length of time in which the C-V2X signal traveled fromthe road side equipment to the motor vehicle; receiving the distancesignal; and estimating a position of the vehicle, the estimating beingdependent upon the distance signal.
 9. The method of claim 8 wherein thedistance signal indicates a distance dependent upon the length of timein which the C-V2X signal traveled from the road side equipment to themotor vehicle.
 10. The method of claim 8 wherein the estimating isdependent upon an immediately previously estimated position of thevehicle.
 11. The method of claim 8 wherein the receiving includesreceiving the C-V2X signal from a C-V2X base station.
 12. The method ofclaim 8 further comprising providing the estimated position of thevehicle to another application within the motor vehicle.
 13. The methodof claim 8 further comprising determining, based upon the estimatedposition of the vehicle, a traffic lane in which the motor vehicle istraveling.
 14. The method of claim 8 wherein the estimated position ofthe vehicle is accurate to within less than one meter.
 15. On-boardequipment in a motor vehicle, the on-board equipment comprising: a C-V2Xcommunication device configured to receive a first signal from road sideequipment having a known position, the C-V2X communication device beingconfigured to transmit a second signal indicative of a length of time ittook for the first signal to travel from the road side equipment to theC-V2X communication device; and a GPS device communicatively coupled tothe C-V2X communication device and configured to: receive the secondsignal from the C-V2X communication device; and estimate a position ofthe vehicle, the estimating being dependent upon the second signal fromthe C-V2X communication device.
 16. The on-board equipment of claim 15wherein the second signal indicates a distance dependent upon the lengthof time it took for the first signal to travel from the road sideequipment to the C-V2X communication device.
 17. The on-board equipmentof claim 15 wherein the estimating is dependent upon an immediatelypreviously estimated position of the vehicle.
 18. The on-board equipmentof claim 15 wherein the C-V2X communication device is configured toreceive the first signal from a C-V2X base station.
 19. The on-boardequipment of claim 15 wherein the GPS device is configured to providethe estimated position of the vehicle to another application within themotor vehicle.
 20. The on-board equipment of claim 15 further comprisingan electronic processor communicatively coupled to the GPS device andconfigured to determine, based upon the estimated position of thevehicle, a traffic lane in which the motor vehicle is traveling.
 21. Theon-board equipment of claim 15 wherein the estimated position of thevehicle is accurate to within less than one meter.